The control of weed growth is an important factor in agriculture. Large areas of plant matter including valuable plants, such as crops, and weeds are usually sprayed with expensive and toxic chemicals in order to control the weed growth. However, ideally only the weeds should be sprayed, but this is difficult if the weeds grow amongst the valuable plant matter. An automated device that is able to distinguish weeds from the valuable plant matter in a quick manner could be used to restrict the spraying of the chemicals to the weeds only and consequently would offer a significant commercial advantage.
Further, it is also of general advantage to be able to distinguish in an automated manner particular plant matter from other matter so that the particular plant matter can be treated differently to the other matter.
PCT International Application Number PCT/AU2007/001075, also owned by the present applicant, discloses an optical device for discriminating specific plant matter from other matter. The optical device comprises laser diodes that emit light having three wavelengths and a plurality of light beams. Each light beam has the three wavelengths directed to the plant matter. A detector detects light beams that are reflected back from the plant matter. A processor then processes the reflected intensities and compares the detected intensity ratios at the three wavelengths with a library of such intensity ratios of known plant matter whereby the device is enabled to discriminate a particular type of plant matter from other matter.
The present disclosure provides a further technological improvement.